Looks to me like RA thinks you have a run a number of years out into the future. If you go under "graphs" and tell it to graph date/distance you get about the same thing as your summary page. However, if you limit it by date to stop at 11/30/06, the graph looks normal.
Why don't you try deleting your runs from 11/30 and re-enter them in case you accidentally put them in for the year 3006 or something... I pick those because when you list your workouts by dates, they are at the top of the list.
If that doesn't work for you, I have no clue!